Tool grinding device



1941- J. v. cARLsoN 2,253,687

TOOL GRINDING DEVICE Filed April 3, 1939 3 Sheets-Sheet 1 I I l mu v WITNESSES: INVIENTOR:

" John 'Mflarls'pn I BY WM ATTORNEYS.

1- J. v. CARLSON 2,253,687

TOOL GRINDING DEVICE Filed April 5, 1959 s Sheets- Sheet s WITNESSES: INVENTOR-Q I Jimn Vflarlson;

I B Y ATTORNEYS.

Patented Aug. 26, 1941 TOOL GRINDING DEVICE John V. Carlson, Chicago, 111., assignor to Union Special Machine Company, Chicago, 111., a corporation of Illinois Application April 3, 1939, Serial No. 265,702

. 2 Claims.

This invention relates to grinding devices useful in reconditioning various kinds of cuttin tools including so-called acorn threading dies such 'as commonly employed in small automatic screw machines and thread chasers of collapsible threading dies.

To sharpen acorn dies for example, it has heretofore been the custom to grind back the leading edges of the lands, with the result that said edges were quickly brought below the centers'of the dies, and the dies thereby soon rendered 7 useless.

The chief aim of my invention is to obviate this drawback, which desideratum I attain as hereinafter more fully disclosed, through provision of a simple and reliable grinding device whereby only the chamfered or tapered first threads of the dies are reground with formation at the same timeof relief clearances rearward of the cutting edges. Thus with the device of my invention verylittle metal is cut away at each grinding and the useful life of the dies correspondingly prolonged.

Another object of my invention is to enable, through provision of improved adjustment facilities, the adaptation of a grindi device having the above attributes for operation on both right and left hand threading dies of different sizes, and for cutting at any desired angle to recondition the dies for the most emcient cutting action upon, different materials.

Other objects and attendant advantages will appear from the following detailed description of the attached drawings, wherein Fig. I is a perspective view of a grinding device conveniently embodying my invention.

Fig. II is another perspective view of the device as it appears from another angle.

Fig. III shows the device in topplan,

Fig. IV is a fragmentary sectional view taken as indicated by the angled arrows'IV-IV in tion and partly in section showing how an acorn threading die is sharpened in the device.

Fig. XI is a. detail sectional view taken as indicated by the angled arrows XIX1 in Fig. X.

Figs. XII and XIII are detail sectional views taken as indicated respectively by the angled arIoWsXIL-XII and. XIIL-XIII in Figs. I and III.

Fig. XIV shows the front end of an acorn die after having been sharpened in the device.

Fig. XV is a perspective view of an auxiliary or alternative part for holding chasers oi. collapsible dies in the device; and

Fig. XVI is a perspective view of the die chaser after having been sharpened in accordance with my invention.

As herein illustrated my improved tool-grind-' ing device has a base I in the form of an oblong plate arranged to be supported on the top of a table or. work bench and secured thereto at corners by screws 2. Mounted on the base I in one corner is a unit 3 for supporting the tool which is to be ground; while the diagonally opposite corner of saidbase is occupied by a unit 4 for supporting the cutting implement by which the grinding is effected.

The tool supporting unit 3 includes an oblong slide carriage 5 which is disposed lengthwise of the base I and has a pendent tongue 6 in engagement with a guide slot 1 in said base, see Figs. I and III. The carriage 5 of the unit 3 is-adjustable relative to the unit by means of a hand screw 8 whereof the shank is threadedly engaged in a fixed bearing lug 9 at the right hand end 7 coordination with an index mark I 6 on said car-- riage. For the purpose of angularly shifting the sector l3 and for fixing it in shifted positions, I have provided screws ll and it which bear against the straight edge IQ of saidsector at opposite sides of the pin l2, and which are engaged in studs 20,and 2| on the carriage 5. Rising from the sector l3-is a clevised bearing post 22 whereon is fulcrumed, by' means of a transverse pin 23, an arm 25;. which, see Fig. V, has

a V-groove 26 in its top constituting a cradle for the cylindric shank 27 of a horizontal axis tool holder or chuck 2,8 with a threaded enlargement 29 at its forward or outer end engaged by a chuck nut 30. At the lower part of its outer or swinging end, the arm 25 is formed with a projecting lug 3! which is centrally notched as shown to clear the shank of an adjusting thumb screw 32 engaging axially downward into a boss 33 on the sector l3, see Figs. I and II. A helical spring 34 in. compression between the bottom of the lug 3| and the top of the boss 33 tends to urge. the arm 25 upward to maintain the top of said lug in contact wth the head of the adjusting screw 32. The tool holder 28 is rotatably held in the v notch 26 of the arm 25 by a hold down means which includes a bar 35 pivotally connected at one end by a transverse pin 36 to an ear 3'! on the arm 25 and engaged at its swinging end by a retractable latch hook 38, which, see Figs. 1 and II, is pivoted at 33 to laterally projecting ear 4!) on said arm somewhat above the projection 3|.- A spring shown at 4| in Figs. I and II tends to keep the latch hook 38 in engaging position. At an intermediate point, the bar 35 carries a pair of spring pressed plungers 42 which bear downwardly upon the cylindrical shank 21 of the chuck 28 as shown in V Fig. XIII and by friction serve to prevent accidental rotation in the arm 25.

As herein exemplified the tool holder 28 is in the form of a chuck capable of receiving hollow annular threading dies of the acorn type such as the one shown at D, Fig. V'lI, X having a series of circumferentially spaced chased lands L, the chuck nut 30 being internally configured to wedge fit over the tapered end of said die in the manner illustrated in Fig. X. At its front end, the threaded head portion 29 of the chuck shank 21 is provided with a pair of diametral key projections 45 adapted to engage the usual notches N at the back of the die D to prevent relative rotation of the latter. To the rear end of the chuck shank 21 is aflixed by means of a set screw 46a, an indexing disk 46' (Figs. II, III and IX) having four notches 41 corresponding to the four lands on the illustrated die D. Lodged in a slot 48 at the bottom of the arm 25 is a slide bar 49, which, see Fig. XII, is subject to a compression spring 50, whereby a sharp upward projection on said bar is yieldingly urged toward the exposed face of the indexing disk 48 and adapted to successively engage the notches 41 of the latter as shown in Fig. II when the chuck is turned for successive presentation of the die lands to the grinding implement in a manner presently explained.

The unit 4 comprises a carriage 52 having a longitudinal slot 53 in its bottom for capacity to straddle the vertical longitudinal rib 55 'of a guide rail 56. As shown in Figs. I and III, the

'rail 56 is pivoted at one end to a vertical screw be laterally shifted horizontally about the stud 51 as an axis. A headed screw shown at 62 and engaging a transverse undercut slot 63 in the base flange of the rail at its swinging end, serves to hold the latter down on the pad. From Figs. I and IV it will be observed that the rib 55 of the rail has V-groove raceways, 64 and 85 in its opposite sides engaged by hearing balls 88 and 61 held in spaced relation by suitably apertured retainers 68 and 69 respectively. The balls 81 also engage a raceway .10 atone side of the slot 53 in the bottom of the carriage 52. .The

screws 14 whereof the shanks pass upwardly through clearance holes in said gib and engage into the carriage 52. By virtue of the provisions Just described, it is possible to preclude both up and down and side-wise play of the carriage 52, and to take up for wear of the balls 58 and 81 and of the raceways in which they travel. As shown in Figs. I, II and IV, the carriage 52 is provided with a. central depression 15 of semihexagonal configuration in its top to serve as a cradle for the diametrically reduced cylindrical forward end portion '18 of the casing of a horizontally-arranged high speed rotary or turbine motor 11 which may be operated by compressed air or other pressure fluid medium supplied through a connecting hose I8, and which is controllable by a throttle valve shown at 18. The motor 11 is held in place by a clamp block 88 with a semi-hexagonal central recess 8| in its 3 bottom to engage over the reduced front end portion I5 of the motor casing. said block being secured to the carriage 52 by a pair of screws 82. The threaded outer end of the shaft 83 of the motor 11 carries a chuck 84 for receiving the shank of a grinding wheel 85, said shaft thus constituting the spindle for the grinding wheel and being aligned axially in the direction of movement of the carriage 52. The rearward travel of the carriage 52 is limited by a fixed stop 88 at the rear or pivoted end of the rail 58, and its forward travel toward theunit 3 is limited by a stop screw 81 which is adjustable in a bearing 89 at the front end of said rail.

In preparing the apparatus for grinding an acorn die, the die is secured in the chuck 28 as shown in the drawings and the indexing disk 48 adjusted circumferentially of the shank 21 of the tool holder 28 with its notches in proper relation to the lands of said die and fixed by means Y of the set screw 46a. The carriage 5 of the unit 3 is. next properly adjusted on the bed plate 1 relative to the unit 4 by means of the hand screw 8, and fixed in the desired position of adjustment by the clamp screws in. The sector i3 is in turn adjusted about its pivot I2 by means of the set screws l1 and I8 and with the aid of the scale graduations on its edge and the mark I6, to predetermine the desired angle of grinding. The arm 25 of the unit 3 is next adjusted vertically by means of the thumb screw 32 to shift the axis of the die D either above or below the axis of the grinding tool depending upon whether the die is of the right hand or left hand variety. With the foregoing preparations completed. the carriage 52 of the unit 4 is moved forwardly on its track rail by hand from the normally retracted position in which it is shown in Figs. I

balls 66, on the other hand, engage a raceway H in a gib 12 which is adjustable laterally of the slot,53 in the slide 52 by means of a pair of screws 13. The gib I2 is held in place by cap.

and III to bring the grinding wheel into the opening of the die and into proximity with the land L which is. to be ground, the stop screw 81 having been previously set to limit such forward movement of said carriage. The guide rail 55 of the unit 4 is thereafter shifted on its pivot 51 by means of the hand screw 68, thereby causing the grinding wheel 85 to be moved laterally into grinding engagement with the first land of the die as shown in Figs. X and XI. After the desired depth of grind is attained, the chuck 28 is turned in the arm 25 to bring thenext land of the die into position to be operated upon by the wheel 85 which land is then ground to the same extent as the first. This-procedure is repeated until all the remaining lands of the die have been refinished. In this connection it will beapparent that any desired cutting angle may be predetermined by rotatively shifting the sector i5 about its fulcrum l2 by which the inclination of the chuck axis is changed relative to that of the grinding wheel 85. Moreover, by vertical adjustment of the arm 25 of the unit 3, it is possible to determine any desired amount of clearance behind. the cutting edge at the leading thread of the die in a manner which will be obvious from Fig. XI. Furthermore, by adjusting the screw 87, the advance of the carriage 52 of the unit 4 may be limited with absolute accuracy to confine the grinding to the first thread of the die and thus prevent injury to the other threads.

The device is of course not restricted to grinding of the four land dies, since in practice disks 46 with different numbers of notches B1 are furbed; 'means'for effecting vertical adjustment of said holderto determine the depth of relief, endwise adjustment for setting the point of grindnished for use with dies with correspondingly different plural lands.

In Fig. XV there is illustrated a holder 9!) suitable for individual chasers of dies of the collapsible type such as shown at C in Fig. XVI. The holder 90 has a shank 9| corresponding in diameter to that of the shank 21 of the chuck 28 for fitment into the recess 26 of the arm 25 of the unit 3, and an oblong head 92 with a screw operated means 93 for clamping the chaser. The component chasers of each collapsible die are successively ground in the device Without change in its setting, and, of course, without indexing of the holder.

Having thus described my invention, I claim:,

1. A self-contained unit for interiorly grinding hollow tools, such as thread cutting dies, for attachment to a table or the like, comprising an oblong rectangular bed; a rotary holder for the tool mounted on the bed at one comer .with its axis of rotation extending longitudinally of the ing action, and circular adjustment to determine the grinding angle; a fixed track at the diagonally opposite corner of the bed arranged at an acute angle to the axis of the rotary tool holder; and a carriage for supporting a grinding movement of the grinding wheel into and out of the hollow of the tool during the grinding.

2. A self-contained unit for interiorly grinding hollow tools, such as acorn thread cutting dies, for attachment to a table or the like, comprising an oblong rectangular bed; a rotary holder for the tool; a carriage adjustable longitudinally of the bedin one corner of the latter; a vertical axis swivel support for the tool holder on the carriage; means for effecting vertical adjustment of said holder to determine the depth of relief, endwise adjustment for setting the point of grinding action, and circular adjustment to determine the grinding angle; a fixed .track in the diagonally opposite corner of the bed arranged at'an-acute angle to the line of adjustment of the aforesaid carriage; a grinding wheel; a support for the grinding wheel; and a carriage on which the support for the grinding wheel is pivoted for angular adjustment in a horizontal plane,

JOHN V. CARLSON. 

